What was LEGO’s first construction toy made from plastic, introduced in 1949?

LEGO’s first plastic construction toy, introduced in 1949, was called Automatic Binding Bricks.

The bricks were produced by LEGO after the company began experimenting with plastic injection moulding. They were based partly on a British design called Kiddicraft Self-Locking Bricks, but LEGO developed its own version and sold it under the Automatic Binding Bricks name.

These early bricks could stack, but their clutch power was limited compared with modern LEGO bricks. In 1958, LEGO patented the improved stud-and-tube coupling system that made models stronger and more stable. That later design became the foundation of the modern LEGO System in Play.

Automatic Binding Bricks are sometimes confused with the modern LEGO brick. The name refers specifically to the 1949 product, while the familiar interlocking brick design belongs to the improved system developed later.